| 15 Sep 2026
Mainz Convective Transport and Scavenging (MCTS version 1.0) – Introduction and Evaluation of the new Column Model for Convection-Chemistry-Interactions
Abstract. Convective systems can rapidly redistribute atmospheric trace gases. For soluble species, not only does convective transport play a key role, but also the interactions with cloud hydrometeors, i.e. scavenging. Global chemistry-climate models have difficulties reproducing observed vertical profiles of soluble trace gases under convective influence. One example is the model EMAC (ECHAM MESSy Atmospheric Chemistry). There are two possible reasons for this issue: (1) the lack of retention and multi-phase transport in the model and (2) the subsequent treatment of the convective transport and the convective scavenging. We present the new column model Mainz Convective Transport and Scavenging (MCTS), which overcomes these shortcomings. MCTS considers transport of trace substances and their scavenging via the ice and liquid hydrometeors quasi-simultaneously. Furthermore, the new model takes retention and multi-phase transport into account. MCTS is evaluated against aircraft observations from the NASA SEAC4RS campaign. WRF-Chem cloud-resolving output was used as meteorological input data for MCTS to accurately represent the convective storm. The new column model performs reasonably well given that it was originally designed for the application in a global model and not for the inter-comparison with a single convective storm. Additionally, MCTS is compared to the convective transport and scavenging in the chemistry-climate model EMAC. Both models affect insoluble species similarly, but have a different effect on the soluble species. Sensitivity simulations with MCTS demonstrate that the time scales of convective transport and the dissociation reactions within the droplet have a major effect on the simulated tracer profiles. MCTS can represent the competition between these two process types, which is a benefit for the calculation of vertical profiles of soluble tracer profiles compared to EMAC. MCTS opens the path for a wide range of future studies, for example, sensitivity studies regarding the ice phase scavenging, which is fraught with high uncertainty. In the long run, we aim to improve the representation of convective transport and convective scavenging in global chemistry-climate models with MCTS.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Geoscientific Model Development.
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